RE: Quandary...
I use the 12z as the master and the 9Z as the slave. When he was able to fly himself I just bound the plane to his TX and he was off and running with the 9Z. There is a 7 channel TX module for the 9 of 2.4. I can't remeber how much.
As for the the 617, you have preset for throttle failsafe and hold on the rest of the channels, good enough for me and at 70 bucks?
I don't think you are going too get much for the 9z, but you never know.